1. Field of the Invention
The invention relates to a joint support and more particularly, to a knee joint support with a gear wheel adjustment mechanism for limiting the pivot range of a distal splint in relation to a proximal splint.
2. Description of the Related Art
Joint supports of this type have been proposed as knee orthoses, which for instance are applied after cruciate ligament operations and permit a movement of the lower leg in relation to the upper leg under controlled conditions and furthermore stabilize the knee. The splints arranged on either side of the knee articulate together at the level of the knee joint and toward their free ends are strapped firmly on the upper and, respectively, lower leg. The pivotal joint in this respect permits flexing and extension of the leg for a predetermined range of pivoting which can be set.
The German patent publication 19,606,092 AI discloses a joint support of this type, in the case of which an adjustment lever, on which a counter-abutment is formed to limit the free range of pivoting, possesses a slot, which extends at a certain angle to a slot in the distal splint. A set screw extends through the two slots. By resetting the position of the set screw within the slots the adjustment lever and with it the counter-abutment can be pivoted about the pivot axis of the joint support with a high degree of precision and steplessly. In this respect it is possible to pivot the splint so far in the extension direction that an over-extension of the limb is ensured. Furthermore this arrangement ensures that the adjustment lever can be reliably fixed simply by somewhat doing up the set screw on the distal splint. This known joint support does in itself provide many advantages over other prior art joint supports, but does however entail using a tool in the form of an allen key for releasing and tightening the set screw. Such a tool is however not always to hand when the limit of the pivot range is to be reset.
Accordingly one object of the invention is to provide a joint support of the type initially mentioned, in the case of which setting of the adjustment lever in relation to the distal splint may be undertaken in the simplest possible fashion and without using a tool.
In the joint support of the invention the adjustment mechanism comprises a manually set gear wheel drive with a drive gear wheel mounted in a rotatable fashion on the distal splint and in engagement with gearing means on the adjustment lever.
With the aid of the adjustment mechanism of the invention the adjustment lever and accordingly the counter-abutment as well may be steplessly reset with the fingers and without having to employ any sort of tool. The limit to the range of pivoting, which is reached on abutment of the adjustment lever""s counter-abutment against the abutment element on the proximal splint, may consequently be reset purely manually and steplessly within a certain angular range, as for instance within fifteen degrees.
It is convenient for the adjustment mechanism to comprise a self-locking gear drive and more especially in the form of a rotatable worm and by means of a worm wheel segment attached to the adjustment lever. By means of such a gear wheel drive the adjustment lever may be set with great precision and quite easily, such a gear wheel drive offering the further advantage of a self-locking action. This means that the load, which is applied by the limb to the splints, will not cause any loss of setting of the adjustment holding. Additional means to prevent for locking the gear wheel drive are hence unnecessary.
As an alternative to this it is however quite possible to utilize a other manually operated gear wheel drives instead of a worm and worm wheel drive and in the partial or total absence of a self-locking action to provide suitable catch members, which may be manually brought into and out of engagement with the gear wheel drive.
A particularly simple embodiment is one in which the driving drive part includes a shaft which is rotatably mounted on the distal splint to extend athwart the longitudinal axis of the distal splint, such shaft bearing the drive gear wheel, and more especially the worm. In at least one of its end parts, and preferably in both end parts, such a shaft may carry a knurled wheel which is able to be turned with the fingers to turn the drive gear wheel.